Which US environmental law mandates filtering municipal drinking water obtained from surface waters?

The Safe Drinking Water Act is the correct choice because it specifically focuses on ensuring the quality of drinking water in the United States. This law sets the framework for regulating the nation's public drinking water supply, including requirements for filtering water obtained from surface sources. Under this act, the Environmental Protection Agency (EPA) is authorized to set national health-based standards for drinking water to protect against both naturally occurring and man-made contaminants.

The other laws mentioned serve different purposes. The Clean Water Act primarily aims to restore and maintain the integrity of the nation's waters by preventing point and nonpoint source pollution but does not directly govern drinking water quality. The National Environmental Protection Act establishes a framework for environmental protection assessments but does not specifically address drinking water standards. The Endangered Species Act aims to protect threatened and endangered species and their habitats without directly regulating drinking water treatment processes.